title: Extracellular YB-1 blockade in experimental nephritis upregulates Notch-3 receptor expression and signaling.
abstract: BACKGROUND
  Notch receptors are involved in kidney development and pathogenesis of inflammatory glomerular diseases. Given the secretion of Y-box (YB) protein-1 following cytokine stimulation and subsequent extracellular association with membrane receptor Notch-3 in vitro, we elucidated functional effects of YB-1 targeting on the Notch-3 signaling pathway.
  
  
  METHODS
  Rat mesangial cells were challenged with a monoclonal anti-YB-1 antibody (YB-1-mAb) and analyzed for YB-1 and Notch-3 expression. Notch-3 expression in mice with a targeted disruption of one YB-1 allele (YB-1(+/d)) was compared with their wild-type littermates. Furthermore, YB-1-mAb was applied during mesangioproliferative anti-Thy1.1 nephritis, and glomerular Notch-3, Notch target genes and YB-1 expression were analyzed by immunohistochemistry, quantitative real-time PCR and immunoblotting.
  
  
  RESULTS
  Upon challenge with YB-1-mAb, rat mesangial cells showed an increased expression of YB-1 and Notch-3 protein. Concordantly, we found a significant upregulation of Notch-3 expression in renal cells of YB-1(+/d) mice. YB-1-mAb treatment in anti-Thy1.1 nephritis resulted in enhanced mesangial Notch-3 expression and differential Notch target gene activation (HES2/Hey-2). Notably, YB-1 mRNA content did not differ between groups; however, glomerular YB-1 protein was significantly increased, suggesting a posttranslational mechanism.
  
  
  CONCLUSIONS
  Extracellular targeting of YB-1 potently induces glomerular Notch-3 receptor expression, Notch signaling and YB-1 stabilization, most likely via an autoregulatory feedback mechanism.
authors.affiliation: Department of Nephrology and Clinical Immunology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Raffetseder
authors.forename: Thomas
authors.initials: T
authors.lastname: Rauen
authors.forename: Peter
authors.initials: P
authors.lastname: Boor
authors.forename: Tammo
authors.initials: T
authors.lastname: Ostendorf
authors.forename: Lydia
authors.initials: L
authors.lastname: Hanssen
authors.forename: Jürgen
authors.initials: J
authors.lastname: Floege
authors.forename: Abdelaziz
authors.initials: A
authors.lastname: En-Nia
authors.forename: Sonja
authors.initials: S
authors.lastname: Djudjaj
authors.forename: Björn C
authors.initials: BC
authors.lastname: Frye
authors.forename: Peter R
authors.initials: PR
authors.lastname: Mertens
mesh_terms: D000483:Alleles; D000818:Animals; D005110:Extracellular Space / Q000378:metabolism* / Q000502:physiology; D018390:Gene Targeting / Q000379:methods; D007678:Kidney Glomerulus / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009393:Nephritis / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology*; D051840:Y-Box-Binding Protein 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: C499373:Notch3 protein, mouse; D000071656:Receptor, Notch3; D051880:Receptors, Notch; D051840:Y-Box-Binding Protein 1